For some time it has been known to provide loose dust, e.g., loose corn starch dust, on an outer surface of a film, in order to facilitate its subsequent processing on high speed packaging machines. That is, dust applied to the surface of the film lowers the film-to-film coefficient of friction, i.e., acts as a slip agent (lubricant), as well as improving the resistance of the film to "blocking", i.e, as an anti-blocking agent. Blocking is an undesirable adhesion between layers of plastic, particularly rolled up film, that may develop during storage.
For some time it has also been known to incorporate particulate antiblocking agent into the resin. The incorporated antiblocking agent functions by forming minute protrusions that maintain separating air spaces that interfere with adhesion, i.e., blocking.
However, the application of dust to the film is detrimental to the quality of the atmosphere in which the film is manufactured and used, and the dust is subject to sloughing off of the film during shippage, etc., and other undesirable effects. Furthermore, films having antiblocking agent incorporated into the resin do not possess a desired combination of slip and antiblock properties. Thus, it would be desirable to reduce or eliminate dust on the surface of the film, while providing the film with desired slip and antiblock properties.
It has also been known to provide the film with a slip agent, which is generally provided in at least the outer layer(s) of the film. The slip agent migrates to one or more outer surface(s) of the film, i.e, "blooms" to one or more outer surfaces, thereby decreasing the film-to-film coefficient of friction, i.e., resulting in a film which slides more easily against itself and other materials. However, it has been found that: (1) the desired coefficient of friction is not obtained until the slip agent is given adequate time to bloom to the film surface, and (2) the blooming of the slip agent to the surface of the film can adversely affect the printability of the film, as ink adhesion can be reduced by the presence of the slip agent.
Thus, it would be desirable to provide a film which exhibits a low film-to-film coefficient of friction, as well as a low film-to-equipment/metal coefficient of friction, along with good antiblock properties, without having loose dust on the surface of the film. It would be still more desirable to provide a film which exhibits low film-to-film coefficient of friction without the presence of a slip agent which interferes with the printability of the film.